(Updates with New York mayor's comments, flight delays, temperature forecast)

By Victoria Cavaliere and Barbara Goldberg

NEW YORK/MAPLEWOOD, N.J., Jan 22 (Reuters) - Residents of the northeastern United States on Wednesday dug out from a deadly winter storm that dumped more than 15 inches (38 cm) of snow in some places, with frigid temperatures forcing school closings and extensive flight delays and cancellations.

At least two deaths were blamed on the weather, which made roads treacherous. Near Emmitsburg, Maryland, a driver lost control and slammed into a tractor-trailer, state police reported. In Versailles, Kentucky, a woman's car hit a tree after skidding on an icy highway, local police said.

"It's brutal out here," said Ian Chapin, 28, an appliance repairman braving stiff winds as he pumped fuel into his work vehicle at a gas station outside Philadelphia.

The deep chill and heavy snow on Wednesday closed schools in Philadelphia and many suburbs throughout New Jersey, Rhode Island and other states.

New York City pushed toward normalcy, opening its schools, but the snowstorm that dropped 11 inches (27 cm) of powder in Central Park touched off some complaints about unequal treatment by new Mayor Bill de Blasio.

In the toniest part of the city, Manhattan's Upper East Side, some residents claimed that their unplowed streets were being ignored as part of the mayor's oft-repeated campaign theme to address issues of inequality.

De Blasio conceded in a statement that, after visiting the neighborhood and talking to residents, "more could have been done to serve the Upper East Side."

He said he ordered city sanitation workers to "double-down" on cleanup efforts on the area.

"Our crews will remain on the streets around the clock until the roadways are clear in every neighborhood, in every borough, across New York City," he said.

Storms have famously complicated the lives of New York mayors. In 1969, a huge storm created a political crisis for Mayor John Lindsay, who was faulted for the city's slow response. In 2010, Mayor Michael Bloomberg came under fire for his handling of a blizzard that halted some subway service for days.

But the snow blanketing the city's icy Times Square failed to deter tourists such as Pablo Magnelli of Buenos Aires, who was traveling with his family.

"We are freezing. But, still, it's a very nice city," Magnelli said. "It was a dream to come here, so we will go out today to the sights - Times Square, the Brooklyn Bridge. We want to see the city."

The single-digit temperatures gripping huge swaths of the nation will prove relentless, according to Accuweather.com Senior Meteorologist Alex Sosnowski.

"A total of three waves of Arctic air will blast across the Midwest and Northeast into next week," he said.

Temperatures are likely to stay below freezing in such cities as Minneapolis, Chicago, Milwaukee, Detroit and Cleveland through the end of the month, with highs most days only in the teens, he said.

"In Boston, Pittsburgh, Philadelphia, New York City and Indianapolis, temperatures may only surpass the freezing mark on one or two days through Jan. 31," Sosnowski added.

U.S. airports reported nearly 4,400 flight delays or cancellations on Wednesday, with New York's LaGuardia Airport and Newark Liberty International the hardest-hit, according to FlightAware.com.

Commuters shivered while waiting for delayed trains into New York City.

"It was cranky and crowded," said Linda Beck, 37, of South Orange, New Jersey, a producer for Nickelodeon stuck on a train for an hour and a half. "Even the conductors were gripey. They couldn't move from train to train it was so crowded."

The heaviest snowfall was recorded in the Boston suburb of Norwell, Massachusetts, with 18.3 inches (46.4 cm) and Manalapan, New Jersey, near the Atlantic coast, which measured 15.8 inches (40.1 cm), according to the National Weather Service. (Additional reporting by Ellen Wulfhorst, Marina Lopes and Zach Cook in New York, Dave Warner in Philadelphia, Ian Simpson in Washington, Daniel Lovering in Cambridge, Mass., Alice Popovici in Maryland, Tim Ghianni in Nashville; Editing by Scott Malone, Nick Zieminski and Gunna Dickson)